How Wheat Kernels Sing Is a Sign of Their QualityBy Erin Peabody
March 30, 2006
Pearson--whos an agricultural engineer at the agencys Grain Marketing and Production Research Center in Manhattan, Kan.--has developed an acoustics-based sorter that can distinguish between clean wheat kernels and those that have been nibbled on and spoiled by insects.
The idea behind the novel technology is simple. A wheat kernel thats whole and intact will make a slightly different, high-pitched ping when striking a steel plate than the sound made by a kernel thats been tunneled through by an insect.
Because individual kernels are so small, lightweight and hard, any acoustic energy they emit is inaudible to human ears. So, Pearson made sure to outfit his sorting system with a special microphone that can pick up ultra-sonic sounds at exceptionally high frequencies.
After assessing the kernels acoustic qualities, the sorter will shunt the insect-damaged wheat kernels from a random sample into one bin, and send acceptable kernels into another. It can even pinpoint kernels with tiny insect larvae hiding inside them, a feat that, for grain inspectors, is like trying to find a needle in a haystack.
Every year, more than $1.5 billion worth of U.S. wheat and other grains must be discarded or downgraded because of post-harvest damage by insect pests. Despite preventive measures, the pestsranging from moth larvae to small flour beetlesstill manage to find their way into grain storage facilities.
Now, most grain inspectors must laboriously sift through samples of grain by hand, relying on the naked eye to spot wheat kernels that have been spoiled by insects. It can take more than 20 minutes to examine a 100-gram sample, or one weighing about one-quarter of a pound.
Pearsons sorter can analyze the same sample in about 75 seconds, or at a rate of 40 kernels per second. And it successfully detects damaged kernels 87 percent of the time.
The technologywhich would undoubtedly lead to more accurate estimates of insect damage in wheat loadsis now ready for a private-sector partner to help bring it to market.
ARS is the U.S. Department of Agricultures chief, scientific research agency.